Question-answering over knowledge graphs is a specific, vastly explored [1]}, [2]} subfield of non-extractive open-domain question answering.
Popular knowledge graphs, based on Wikipedia, include DBpedia [3]}, Wikidata [4]} and YAGO [5]}. A comparison of them has been composed by [6]}. Specific datasets for testing question answering over knowledge graphs are WebQuestions [7]} and SimpleQuestions [8]}.
Knowledge graphs are, however, also used for fact-aware language modelling [9]} or fact-checking
[10]}, [11]}.
Simple slot-filling without any reasoning (either multi-source facts or resolving aliases) would be a trivial task. It is then used in the opposite direction, for automatically creating knowledge graphs [12]}.
These knowledge bases found their use even in more distant tasks, such as Word Sense Disambiguation [13]}.
Knowledge graph retrieval is then reduced to finding variables given constraints (a subgraph with free variables that needs to be matched over the knowledge base).
